Data is stored on magnetic media by writing on the magnetic media using a write head. Magnetic media can be formed in any number of ways, such as tape, stripe, floppy diskette, and hard disk. Writing involves storing a data bit by utilizing magnetic flux to set the magnetic moment of a particular area on the magnetic media. A typical thin film write head is disclosed in U.S. Pat. No. 5,452,164, by Cole et al., entitled THIN FILM MAGNETIC WRITE HEAD, issued Sep. 19, 1995, herein incorporated by reference in its entirety. The state of the magnetic moment or bit transition is later read, using a read head, to retrieve the stored information.
An important goal of the magnetic storage industry is to improve data density and data rate. For higher data rates it is necessary to minimize write head inductance. One way to accomplish this is to minimize the number of coil turns.
To improve data density, reduced size write head structures and high coercivity media are used. High data density, then, requires high flux to write to the high coercivity magnetic media. To generate higher flux for higher data rates, it is necessary to provide higher current through the turns to provide sufficient magnetomotive force or MMF.
At higher currents, low coil resistance becomes important to reduce power loss and to limit resistive heating. As such, it is necessary to keep the resistance of the coil low. Conventional structure and processes, however, limit reduction of coil resistance to provide high density, in excess of 12 Gb/in21, at high data rates, in excess of 700 Mb/sec.
With a preferred embodiment of the present invention, a thin film write head is provided having a lower pole structure with a yoke and a pedestal pole tip, and having an upper pole structure with a pole tip opposing the lower pedestal pole tip across a write gap layer.
In the preferred embodiment of the present invention, a middle coat insulation layer is located over the yoke of the lower pole structure and adjacent the pedestal pole tip. A trench is formed in the middle coat layer by etching part way into the middle coat layer. A conductor coil is formed on the middle coat so that a portion of the coil is located within the trench and a portion above the trench.
In one preferred embodiment and method of fabrication, the middle coat is planarized and then etched using a resist mask to form the trench. With one preferred embodiment and method of fabrication, after etching the trench, the resist mask is removed and a conductor seed layer deposited on the middle coat. The coil turns are formed within a resist mask formed on the seed layer. The seed layer is etched after resist mask removal to electrically isolate the turns of the coil.
In another preferred embodiment and method of fabrication, after trench etching, conductor material may be deposited on the middle coat and planarized to form the portion of the coil within the trench. A resist mask may be formed and additional conductor material deposited within to form the portion of the coil above the trench.
In a typical embodiment, the trench is formed in the middle coat such that the additional conductor material in the trench added to the coil provides at least a 5% to 10% reduction in the resistance of a coil than without the addition conductor material in the trench. In more preferred embodiments, addition of conductor material in the trench typically provides at least 20% to 30% lower coil resistance.
This allows lower coil resistance without increasing stack height or yoke lengths to improve write head performance.